<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>js练习</title>
    <!-- <script src="demo02.js"></script> --> 
</head>
<body>
    <!-- <script>
        alert("hello javascript!");
    </script> -->

    <!-- <input type="buttom" value="点我一下" onclick="alert('hahaha')"> -->

   <script>
    let name = 'zhuangsan';
    name = 20;
    console.log(typeof(name));

    let str = 'sgshd';
    console.log(typeof(str));

    let c;
    console.log(typeof(c));

    let num = 15 / 2;
    console.log(num);

    let age = 20;
    let age1 = '20';
    let age2 = 20;

    console.log(age == age1);
    console.log(age === age1);
    console.log(age == age2);
    console.log(age === age2);

    let arr = new Array();
    let arr1 = [];
    let arr2 = [1,'20',false];
    console.log(arr);
    console.log(arr1);
    console.log(arr2);
    
    
    
    
    
    
    
    
    
   </script> 
</body>
</html>